Scrub Hub: What should I do to keep my plants alive during the winter?

As time spent sheltering in place stretched on last year, many people took advantage of the extra hours at home to take on caring for something new. No, I’m not talking about a puppy — I’m talking about houseplants.  

Much like pet adoption centers and chess board retailers, plant stores reported seeing a spike in purchasing last year while people staying at home took on new hobbies and responsibilities.

But now it’s winter and that green thumb you thought you had as you nurtured your peace lilies and fiddle-leaf figs over the summer may be starting to look a little… well, brown.

Cilantro grows in Mark Clayton and Julia Spangler's garden in Indianapolis on Thursday, May 28, 2020.

Don’t worry, it’s not too late to save your plants from the hazards of winter.

For this edition of the Scrub Hub, our series dedicated to answering your questions, we spoke with Krishna Nemali, a professor in horticulture and landscape architecture at Purdue University, about how to keep your plants alive throughout the winter.

Here’s what he said:

The short answer

The best thing to do for your plants from the start is to research what they need. 

In the case of outdoor plants that can’t be brought inside, Nemali suggests researching your plant hardiness zone and buying only plants that can survive in that zone’s winter climate. Most of Central Indiana lies in Zone 6a or 5b, according to the U.S. Department of Agriculture.

“If you buy something out of that then they may be sensitive to cold,” Nemali said, “No matter what you do, they will probably die.”

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Light becomes another important factor to monitor throughout the winter, as daylight hours shrink and cloudy weather gets more and more common.

If you can, position your plants to where they get the maximum amount of light each day, and consider adding artificial light sources.

Be sure to monitor your plant’s moisture levels, as well, as plants may not need as much watering in the winter. If your plant starts looking a little droopy or loses stability toward its base, it may be time to hold back on the water.

For more warning signs and tips, keep reading:

The long answer

Nemali breaks down plant care into four main categories: temperature, light, water and nutrients.

Possibly the most obvious change plants experience in the winter is a drop in temperature. Most houseplants, Nemali said, prefer to live between 68 degrees and 75 degrees Fahrenheit. 

If you keep it cold in your home, don’t panic — plants can survive through colder temperatures, such as in the 50s, but they may stop growing to conserve energy.

“They’re just hibernating at that point,” Nemali said.

Once exposed to temperature in the 40s or below, however, most houseplants will show signs of injury or will even die, Nemali said.  

When it comes to outdoor plants, as long as you’ve selected those that can live in your plant hardiness zone they should be able to last the winter.

But if you’re still worried about whether they’ll withstand the next cold front, you could cover them with a light fabric to defend against frost. Be sure to pick a fabric that allows enough sunlight to come through, Nemali warns.  

Bill Ryerson walks through the garden at his Indianapolis home on Friday, May 29, 2020.

Light also changes during winter, as days get shorter and cloudier and the sun shifts its position. You’ll start noticing the effects of low light as soon as 10 days after your plant is exposed to it, Nemali said. If your plant is starting to look elongated and dropping its bottom leaves, there’s a chance it needs a bit more sunshine. 

If your windows aren’t positioned to get enough light during the day, you might want to consider putting your plants under a lightbulb for some hours of the day.

LED lightbulbs, Nemali points out, give out a bright enough light for plants while also consuming less energy. Halogen bulbs, on the other hand, might scorch your plants’ leaves.

When it comes to water and nutrients, as a general rule houseplants don’t need as much during the winter, Nemali said. Because your plant is likely growing less and possibly even hibernating, you are at risk of overwatering it or giving it too many nutrients.

In fact, Nemali said, you could probably get away without giving your plants any nutrients during the winter at all.

“The amount of water and nutrients plants take should be based on how they’re going,” he said. “If the plants are not growing fast, there is no need to also a apply a lot of nutrients and water, that’s only going to cause problems.”

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If your plant is looking sickly but you’re not sure what’s wrong with it, Nemali said there are some specific warning signs for which to watch. 

Yellow leaves could be a sign of low light or lack in nutrients. A nitrogen deficiency, for example, will present itself by yellowing the bottom leaves first. 

Cold temperatures, on the other hand, might make your plant’s leaves curl, droop or grow discolored. 

If your plant is underwatered, its leaves may wilt or get crispy and dry. Overwatering may make your plant have limp, yellow or brown leaves that aren’t crispy. You can also tell if your plant is overwatered if its base gets mushy.

If you’re still stumped, feel free to reach out to Purdue’s horticulture department with questions, Nemali said — they’re happy to help you and your plant make it through the rest of winter. 

Do you have more questions about how to take care of plants during the winter? Ask us! Submit a question to the Scrub Hub through our Google form below. 

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Contact IndyStar reporter London Gibson at 317-419-1912 or lbgibson@gannett.com. Follow her on Twitter @londongibson

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IndyStar’s environmental reporting project is made possible through the generous support of the nonprofit Nina Mason Pulliam Charitable Trust.